There are a variety of conventional water drinking devices for pets available at the market place today. These conventional water drinking devices for pets are generally defective in design in that they are provided with a water inlet which is too small to facilitate the replenishing of the devices with fresh water and the cleaning of the devices, and that they are provided with a water outlet located at the bottom thereof, thereby subjecting the pets to drinking the water contaminated by impurities which precipitate to the bottom of the device. In addition, such conventional water drinking devices for pets as described above are not provided with an apparatus for adjusting the position of the water drinking devices in accordance with the height of a pet.